1. Field of the Invention
This invention relates generally to an optical system for transmitting light emitted from a light source to an optical fiber type waveguide or lightguide and more particularly to improvement of a light source system including a light source and a uniforming device connected to a light-receiving end of the optical fiber type lightguide at an end thereof for receiving light emitted from the light source and emitting light, of which quantity or amount is uniformly distributed in every direction of emission, to the light-receiving end of the lightguide.
2. Description of the Prior Art
A typical optical fiber type lightguide, for example, what is called a "linear pattern outputting lightguide" or a "circular pattern outputting lightguide" (that is, a lightguide having a linear or circular light-emitting end) includes a large number of optical fibers and is adapted to receive and transmit the light received from a light source and output the light from the light-emitting end thereof to an external point.
FIG. 16 is a diagrammatical sectional view of a conventional optical system having such a typical lightguide, wherein light radiated from a lamp 11, which can be regarded as a point source of light, is condensed or converged by a reflecting mirror 12. Further, infrared radiation harmful to optical fibers 18 included in a lightguide 15 is removed therefrom by a heat absorbing glass or an infrared absorbing filter 13. Thereafter, the light is directly incident on an end of the lightguide 15.
Nowadays, the lightguides are widely used for general illumination or lighting. Further, in recent years, the lightguides have become employed as light sources of, for instance, inline inspection systems in automated factories, optical business machines and so on. With such spread of the lightguides, it has become requested that the distribution of the quantity of light emitted therefrom is as uniform as possible in every direction of emission of light. Thus, there have been proposed various optical systems provided with a uniforming means 14 such as a diffusing plate 16, a cylindrical or columnar body 17 made of light-transmitting material (hereunder referred to as a cylindrical or columnar light-transmitting device) or the like in a light source system thereof prior to the optical fibers of the lightguide 15 for uniforming, that is, making the distribution in angle of emitting (hereunder referred to as "emitting angle") of the quantity of light which is incident on a light-receiving end of the lightguide.
Such a conventional light source system including a uniforming means for uniforming the quantity of the light, which is incident on the light-receiving end (hereunder referred to as the "incident end") of the lightguide, has a drawback wherein effects of illumination by the light source are extremely degraded because the quantity of the incident light itself decreases due to the diffusion of the light caused by the diffusion plate, though the uniformity of the distribution in "emitting angle" of the quantity of the incident light in every incident angle of light on the "incident end" of the lightguide as well as that of the distribution in "emitting angle" of the quantity of light emitted from the lightguide is promoted or enhanced with increase of the diffusion coefficient of the diffusion plate. Incidentally, the term "incident end" is further used hereinbelow to indicate a light-receiving end of a device such as a lightguide.
Further, the conventional light source system employing the columnar or cylindrical light-transmitting device has a defect that it has little effect on the enhancement of the uniformity of the distribution of the quantity of the incident light, though the efficiency of illumination is not decreased. The present invention overcomes these defects of the prior art optical system.
It is accordingly an object of the present invention to provide a light source system having an improved light receiving device including a uniforming means which can uniform the distribution of the quantity of the light emitted therefrom to the lightguide in every direction of the emission of the light without decreasing the quantity of the emitted light during the transmission of the light therethrough.